IC211 Spring 2019

HW Lec #4

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1. [20Pts] What's wrong with the function disp() defined below?

   public class Foo {
     double x;
     String s;
     public static String disp() {
       return "[" + s + "," + x + "]";
     }
   }

2. [60Pts] Given the following (partial) defintion of class Time

   public class Time {
     int hh, mm, ss;
     public boolean equal(Time t) { ... }
     public static boolean equal(Time t1, Time t2) { ... }
   }

   Assume code in some other method of class Foo defines A and B as: Time A = new Time(), B = new Time();

   1. How would you call the first definition of equal to compare A and B?

   2. How would you call the second definition of equal to compare A and B?

   3. Give the definition for the first "equal":

      public boolean equal(Time t) {
      
      
      
      }

   4. Give the definition for the second "equal":

      public static boolean equal(Time t1, Time t2) {
      
      
      
      }

3. [20Pts] Suppose I wanted to add a function to the Time class (above) to determine whether Time A comes before Time B. Give the complete method definition I would have to add to the Time class in order to be able to call the function like this:

   A.isBefore(B)